Coupled Thermal and Mechanical Analysis of Composite Cross Sections During Concrete Hydration Using Mathematical Optimization Strategies

Abstract

The thermal and mechanical behavior of young concrete is highly nonlinear. In this article, a new simulation approach for the thermal and mechanical analysis of composite cross sections is shown, which uses energy principles and mathematical optimization algorithms as a consistent physical and methodical base. For the thermal analysis, an energy functional is developed by using the virtual source energy, while the mechanical analysis is performed by minimizing the potential energy. The changes in the thermal strain caused by the temperature differences are considered in the mechanical analysis as tension free pre-strain. By adding the maximum tensile strain to the mechanical material parameter evolution, the flip over of the residual stresses as well as cracking and its development over time can be represented. Furthermore, to reduce the number of unknowns without reducing the approximation order, numerical time integration methods of dynamics are applied to the thermal analysis.